Several dwarf galaxies have been discovered close to our own Milky Way and are adding to our understanding of how galaxies form. But why haven't astronomers seen them before?

Gemini North observatory, on Hawaii’s Mauna Kea, shoots a laser beam into the night sky to create an ‘artificial star’, part of a process that helps astronomers remove blurring from any images of galaxies.
Gemini Observatory and Association of Universities for Research in Astronomy September 17, 2014

A supermassive black hole has been found in an ultracompact dwarf galaxy – the smallest galaxy known to contain such a massive black hole. This finding, published today in Nature, suggests that supermassive…

A dwarf galaxy: a challenge for modern cosmology? This dwarf galaxy ESO 540-31 is more than 11 million light-years from Earth, in the constellation of Cetus (The Whale).
, Luca LimatolaESA/Hubble & NASAJuly 25, 2014

Over the last few years we’ve been studying the orbits of dwarf galaxies and we expecting to find them buzzing at random around large galaxies. But looking out into the universe, we see some dwarfs undertaking…